Mike Ferullo is 64 and has run several marathons, including three in Boston. Saturday mornings, snow or shine, you’ll find him in Franklin Park, running with a group of young men.

As the founder and coach of the Pine Street Inn’s Bulldog Running Club, Ferullo has volunteered hundreds of hours over the past five years helping men replace drug and alcohol addictions with a healthy runner’s high. Club members include residents and graduates of Pine Street’s Stabilization program, a residential addiction recovery unit on the campus of the Shattuck Hospital in Jamaica Plain.

Monday, for the first time, a Bulldog club member ran the Boston Marathon. He’ll never forget it.

Wendy Maeda/ Globe Staff

Stephen Stephenson said that if his knees hadn’t cramped up Monday, “we probably would have run into Armageddon.’’

Stephen Stephenson of ­Dedham ran, and Ferullo jumped in at Mile 23 to finish with him. At the Massachusetts Avenue Bridge, not far from the finish line, the runners were turned back.

A bomb. The word wafted through the crowd. Then two bombs. “I thought it was a hoax,” Ferullo said afterward. “Everyone was so confused and frightened. There were still thousands of people running behind us. Truthfully, I am just in shock. This is beyond belief.”

Stephenson, 29, had started out too fast, and by mile 15, his knees had cramped up. Forced to slow down, he says if he had continued at his regular pace, “we probably would have run into Armageddon.”

Ferullo agrees. “I had to stop three or four times to massage his calves because of spasms, and I swear to God, if we didn’t stop, we would have run right into it.” They were a quarter-mile, “or about four minutes” from the finish line when they were turned back.

“We were all excited near the finish line. Then people were crying, freaking out, and then we lost phone service,” said Ferullo. “There was an enormous amount of confusion. No one knew what was ­going on.”

They were worried about Stephenson’s mother, nieces, and friends near the finish line, but learned they were OK. Neither man heard the explosions.

The week before the race, the two men spoke enthusiastically of the Marathon.

“Coach Mike takes time out of his day for us, and he doesn’t have to,” said Stephenson, a quiet man who is loath to talk about himself. “Part of the reason I wanted to do it is that he’s always wanted to have one of us run the Boston Marathon.”

The step-by-step process of getting sober is sometimes compared to running a marathon. Stephenson is a recent graduate of Pine Street’s Stabilization program. An athletic kid from Dedham, he fell into drug and alcohol use in high school.

Running with the Bulldogs, he believes, has helped his ­recovery. “It keeps me clean,” said Stephenson, who on a ­recent day wore black Nikes and a Red Sox hat. “It’s something positive to be addicted to.”

Daniel Millner, clinical super­visor of the men’s Stabilization program, has seen firsthand the Bulldog club’s value: “In addition to the benefits of exercise and a healthy routine, the club provides camaraderie, and it gives the men a focus as they seek to move beyond their addictions to stable, productive lives.”

Stephenson, who still lives on the Shattuck campus near the Stabilization unit, joined the team in July, and in October, he and Ferullo ran the ­Boston Athletic Association’s Half Marathon. Stephenson finished in 1 hour, 44 minutes. Those in the club — named for Ferullo’s English bulldogs Rocky and Gus — run on Tuesdays and Thursdays and train with Ferullo on Saturdays.

“Stephen is a natural athlete,” said Ferullo, sitting across from Stephenson in his Brookline office. “He’s the real deal when it comes to running.”

But most of the men aren’t, and Ferullo starts them off on what he calls LSD: long, slow, distance running. Newcomers may start at 2 miles the first week, eventually getting to 5 or 6. When a runner achieves the 6-mile mark without stopping, he gets a T-shirt. Ten miles gets him a pair of running shoes.

Ferullo urges the men to run on the treadmill in bad weather and encourages them to cross-train on days they don’t run.

Marathon Sports donates slightly used running shoes, which Ferullo gives the new guys. For brand-new shoes, he holds fund-raisers. In fact, ­Stephenson’s Boston Marathon run was a fund-raiser to benefit the Bulldogs and the Stabilization program. He was given a charity number by John Hancock, which means he had to raise $5,000 for a nonprofit. He did, helped by Pine Street staffers who sent out an e-mail blast.

Along with the shoes and apparel, Ferullo comes with instant credibility. Forty years ago, he had his own addiction issues. “I talk to them as a person who has been there,” he said of his team. “I was in that world, and I could have been in a shelter.”

Growing up in the North End and Revere, Ferullo became involved with drugs and dropped out of school. But he got the help he needed and went on to college and graduate school. He’s been married 25 years and has a 24-year-old son.

“Running played and continues to play a significant role in my transformation and my life,” he said. “It was a big part of me being able to keep away from negative people.”

Today, he’s a licensed social worker with a practice in Brookline specializing in helping men and boys with addictions, anxiety, and depression. An exercise program is invariably part of his prescription. Ferullo also works part time as a social worker for the Watertown public schools.

On any given Saturday, the Bulldogs may have a handful of runners, or as many as 10. ­Ferullo says the physical, emotional, and social aspects of running create a natural antidepressant. “They’re all hanging out together, not getting high, and running gives them a sense of empowerment and self-esteem.”

Today, Stephenson works part time as a landscaper and is looking for his own place to live. “I don’t go to AA,” he said. “Running is a positive thing that helps me stay on the right track.”

Stephenson and Ferullo say they hope to qualify for a marathon in Lowell in October, and Ferullo will train Stephenson for next year’s in Boston. “I’m proud of him,” he said.

Stephenson first marathon was a revelation in so many ways, from cramps to dehydration to explosions. “I ran like 26 miles but I couldn’t actually cross the finish line because of what happened,” he said. “But I’m going to tell people that I finished, and I’m not going to let this deter me from doing it again.”